Heretofore, a synthetic resin substrate having hydrophobicity has sometimes had a trouble attributable to the hydrophobicity. For example, a fluorine-containing resin film as a typical example of a synthetic resin substrate having hydrophobicity, is excellent in transparency, durability, weather resistance, antisoiling property, etc., and by virtue of such characteristics, it has been used as a film for an agricultural or horticultural house instead of a vinyl chloride resin. However, when a fluorine-containing resin film is used for an agricultural or horticultural house, moisture condensation is likely to form on the inside surface of the film as the film has no hydrophilicity, whereby problems are likely to result such that sunlights required for the growth of plants tend to be blocked, or deposited water drops are likely to drop directly on crop plants instead of flowing in the form of a water film on the film surface, to present adverse effects.
To solve such problems, as a method for imparting hydrophilicity to the surface of a synthetic resin substrate, a coating method has heretofore reported in which a mixture of a silica-type sol and a surfactant, is coated on the resin surface, followed by drying to impart hydrophilicity (e.g. JP-A-62-179938, JP-A-5-59202 and JP-A-5-59203).
However, with the hydrophilic film obtained by this method, the hydrophilicity does not last for a long period of time, and in a case where it is used for a synthetic resin which has a long useful life like a fluorine resin film, there has been a problem that costs and time will be required, as it is necessary to carry out recoating periodically.
The present invention is intended to solve the above-mentioned problems of the prior art and to provide a synthetic resin molded material having adequate hydrophilicity, whereby the hydrophilicity will last for a long period of time.